Sampled analog technology is a technique for processing analog input data by a mix of switched capacitor circuits and amplifiers. Directly processing analog signals without intermediate conversion to digital signals can reduce circuit resources compared to use of a digital arithmetic unit of a digital signal processor. Sampled analog technology can be used in various applications where normally digital processing is used. For instance, sampled analog technology can be used for audio, ultrasound processing, etc.
In sampled analog technology, switched capacitors circuits are employed to implement programmable filters for operating on such analog input data. For sampled analog filter banks, there is a trade-off on the size of the coefficients being used and the area used for the given filter. For sampled analog technology, the predominant area used is for these switched capacitors circuits, as the ratios of capacitors in these switched capacitors circuits are what implement the coefficients used. Because of the area and switches used, creating a sampled analog filter bank with a high precision coefficient is costly in area and power. In some cases, sampled analog systems to process or filter sampled analog input data, have a finite resolution related to the finite area available on a chip for the capacitors. Additionally, since the required chip area in a binary switched capacitor circuit increases exponentially with the number of coefficients and the sampling rate depends on the time required to charge and discharge the capacitors, the capacitance of the capacitors which is proportional to the area taken up on the chip should be kept small. Conversely, smaller capacitors exhibit a larger signal-to-noise (SNR) ratio, which can limit how small the capacitors can be in the circuit design.